I have had my betta fish for 5 months and he has been perfectly healthy, but around 5 days ago I noticed my betta fish had a hole near his back end. I tried melafix but he has not gotten any better. Instead he has just lays at the bottom of his tank and no longer swims around like he did. He also did not eat any food yesterday. What should I do so my betta feels better???
I attached pictures of where he lives and the hole in him. Before the hole, I changed the water every week and put a water conditioner in. Before 5 days ago, I have never had a problem. I also believe he has another hole starting near the top of him, by his top fin... Nothing as bad as the one on his back end, but I can see it become lighter like it will open eventually. Thanks

No matter what other treatment is recommended, and that is beyond my limited knowledge, please get him a heater and a thermometer. If he's too cold, it can stress him which can make him suceptible to all manner of things. Just like people, when Bettas get stressed, it lowers immunity. (says the mom of 4 bettas, 3 cats, 2 kids, and one frog, who is about to have to leave all of her non-human children in other people's hands for a week while we go on vacation...and she has managed to catch a cold in the middle of summer)

A betta is most comfortable in water that is around 78. Depending on what his problem is, higher or lower may help, which is where a good heater and thermometer come into play.

It looks like it could be an open wound you can try treating with a Stress Coat which is great for helping to regenerate tissue. Some in this forum say aq salt would also be a good choice but I have never used it so I cannot co-sign on it. I would recommend daily water changes and a nice warm environment. I agree with Shadyr a heater is necessary.

The water conditioner I use has stress coat in it, so whenever I have changed his water I use the stress coat. It has not helped it... I will get a heater, but any other recommendations on how to help decrease the size of the hole?

That's an aggressive bacterial infection. Sorry to say, once it eats into the skin it's pretty hard to heal.

Kanaplex is your best bet to help your fish. It's an antibiotic you can buy retail at pet/fish stores or online that deals with several kind of bacteria. Get onto this really quickly, if you can.

Unless your house is at around 82F constantly, he WILL need a heater. Temperature spikes and swings, especially in the summer months, are notorious for causing this sort of thing, where the fish get run down (infrequent water changes/ammonia load not helping any) and the germs get a good grip on the fish.

If you do get a heater, however, do not raise the temp past 78 while he has this sickness. Heat will speed it up.

weekly water changes isn't enough for his current home. You should be changing the water every other day to every few days to prevent ammonia build-up. If it builds to a certain point his fins can literally burn away or he could have permanent damage to his scales or gills.

I thought that since he has quite a sizeable hole, perhaps on the Betta fish diseases and emergencies would be a better section for advice on how to treat. I am trying the aquarium salt so hopefully that helps!! Thanks so much!!!